Switch control for trailable track switches



2 SI'lEETS SHEET l Ihwcntor G. J. JOHANEK SWITCH CONTROL FOR TRAILABLETRACK SWITCHES July 22, 1952 Filed. Aug. 10. 1949 wZEo Z JOMPZOU(Ittorneg G. J. JOHANEK SWITCH CONTROL FOR TRAILABLE TRACK SWITCHES July22, 1952 2 SHEETS-SHEET 2 Filed Aug.

Zmventor Q n m at FI II uZIo Z JOmkzOu points by the car wheels.

Patented July 22, 1952 SWITCH CONTROL FOR-TRAILABLE TRACK SWITCHESGeorge J. Johanek, Rochester, N. Y.,iassignor to General Railway SignalCompany, Rochester, N. Y.

Application August 10, 1949, Serial No. 109,439

1 Claim.

This invention relates to control circuits, and more particularlypertains to the type of circuits used to control an electricallyoperated railway switch machine from a remote location.

Modern railway practice requires the-use of power operated switchmachines and, in addition, the provision of some means for controllingthe various switches in a given region from a single, remote location.It has also been found desirable to provide means for preventing damageto switch machines in the event that a trailing point train movementforcibly moves the switch points from their last actuated position. Onsomeprior types of trailable switches, mechanical means, such as aspring connection with dash-pot, are provided tobias the switch pointsto their last actuated position, but which permit them to be temporarilyforced to the opposite position by the wheels of passing cars. This typeof switch machine operation has been found to cause a greater thannormal amount of wear as the switch points are continually slammed tothe trailed position by successive car wheels. In other types oftrailable switches, the switch points are immediately moved to theirfull trailed positions independently of the switch operating mechanismby reason of a yieldable spring biased cam connection. With this type ofoperation, it generally is required that the switch machine controllever be manually operated to such trailed position after the passage ofthe train to bring the operating mechanism into correspondence with theswitch points in order that the switch points can then be returned bypower operation to their original position existing before the trailingpoint train movement.

The control circuit organization of the present invention avoids thedisadvantages of the prior art by providing positive operation of theswitch points by the switch operating mechanism immediately followingthe initial trailing of the switch This positive operation of the switchpoints prevents the slamming of the points against the stock rails uponthe passage of successive car wheels, and also provides that theoperating mechanism is in correspondence with the switch points at thetermination-of the trailing point train movement.

Without attempting to describe the present invention in exact detail, itmay be said that when the switch points are forcibly moved from eitherthe full normal or full reverse position, the switch operating mechanismis immediately operated to a corresponding position, which position isof course opposite to that to which it was last actuated. This newposition of the switch operating mechanism positively holds the switchpoints in the full operated position in which they are being trailed.Then when the associated track circuit becomes unoccupied, the switch.

points can immediately be restored by power operation to the'originalposition called for by a remotely located control lever withoutrequiring any action on the part of the operator. -On .the other hand,if the operatorhas already operated the control lever to the newposition in which-,the

switch points are being trailed, then the switch operating mechanism isin a correspondingposition and holding the switch points in thatposition. Thus, no operation is required on the part of the operatorsubsequent to the associated track section becoming unoccupied. V

The features of the present invention may be applied not only toconventional switch machines that are reversible in mid-stroke, but alsoto switches of the type disclosed in Patent No. 1,854,602 to C. W.Prescott, dated April 19,1932, which are ordinarily not so constructedas to be reversible in mid-stroke. Switch machines of this latter typeemploy a yieldable cam connection as shown in the above mentioned patentwhich not only permits movement of the switch points independently ofthe switch operating means, but also causes the switch points to beoperated fully to the opposite positionupon their being moved from theirlast actuated position by a trailing point train movement. as abovedescribed. In order to demonstrate the applicability of the features ofthe present inventionto switches having switch machines of either type,two separate embodiments of this invention are herein disclosed but itshould be understood that, although these specific embodiments have beenemployed in order to permit a specific and complete description ofthisinvention, the features of this invention can readily be applied toOther types of switch machines. I

Other objects, purposes, and characteristic features of the presentinvention will be in part obvious from the accompanying drawing-and inpart pointed out as the description-of this invention progresses. 3

In describing the invention in detail, reference will be made to theaccompanying drawings.- In. these drawings, like reference charactershave been used for corresponding parts in the two separate embodimentsbut distinctive reference characters are used for those parts which areassociated with onlyone or the other of thetwo embodiments. In thesedrawings: a e

Fig. 1 illustrates the switch machine control circuit organization asapplied to a switch machine of the type adaptedfor use in classificationyards and having a yieldable cam connection; and

Fig. 2 illustrates the switch machine control circuit organization asapplied to a switch machine having a yieldable connection and beingreversible in mid-stroke.

For the purpose of simplifying the illustration and facilitating in theexplanation, the various parts and circuits; constituting.theembo'dimentof the invention have been shown diagrammatically and certainconventional illustrations have been employed, the drawings having beenmade more with the purpose of making it easy: to. understand theprinciples and mode of operation, than with the idea of illustratingthe. specific construction and arrangement of parts that would be -em-:

ployed in practice. Thus, the various relaysand their contacts areillustrated in a conventional manner, and symbols are used ;to: indicatecon nections to the terminals of batteries ,or, other.

"injanor mal position contacting the stationary 'contacts lt and H5 whenthe switch points are in correspondingful1-normal positions, and which'j is caused tobe" in a reverseposition contacting stationary-contacts2land --22 when the switch points are in--corresponding full reversepositi'ons'. =However when the switch points are out oiztheir-fullinormalaor reverse positions, as during their operationfromone position to another, thefmovablecontact- I 4 is in itsmid-position --show n- 'by dotted lines.- Thissw-itch box SB may be pfthe type-shown in the Patent No. 2,394,215 ton-J. stevenson datedFebruary 5, 1946, or other su-itable-contacts capable of repeating the"position of the switchpoints can be incorporated -within-theswitchmachine, if desired.

" -"A--switch machi'ne -lever SML located at the---con;trol-ofiiceoperates the pole changing conta cts 3 'and4to-applysteady energy of either 'polarity fromthe battery B to the line wires 5and 6; Thus, with the lever SML in the normal positi'on -N, it isevident-that the line wire -6- will be of positive polarity-with respectto the line wire l'as The energy thus transmitted over-the line wires isapplied to-the= upper windings of the -eontactors'NWR*-and RWRi Thesecontactors are of the polar-biased neutral type such as shown in theprior Patent No. 2,414,583 granted January 21, 1-947, to 'G. E. Duffy,Sr. -Each of thes'e contactors has two independent windings "either-on'eof which'will, when energized with the pi-openpolarity, pick -up-"itsarmature and cause the clo sure-of its various front contacts.However',- the-'energization of either one of these wind- -i'l'lgswiththe opposite polarity will not cause an actuation of the contacts totheir picked up positions: 'Thus,-energization of the line wires 5..anavs with'one polarity causes the actuation of -onecontactor whileenergizati'on of the line Wires off'the': opposite'polarity causes theactuation of the other contactor. This has been illustrated thesimultaneous picking up of both contactors over the control line Wires 5and 6. Thus, with the lever SML in the normal position N, as shown, thecontactor NWR will be picked up because the direction of current flowthrough its upper winding-correspnds to the direction of the arrowincluded within the relay symbol. In order to pick up the contactor RWR,it is necessary to move the leverSML to its reverse position R, in which'case'the'contactor NWR will drop away (because it can not respond toreverse current through itSiWlIldi'IlE) and close its back contact 1,thereby completing a circuit for the energization of the contactor RW'R.

With the switch points SW in the normal posi- -tion: shown inFig. 1, andthe switch machine SM ina corresponding position, the movable con='tactsS and 9-ofthe'swi-tch machine are in their upper position-so thatcontact 8 engages-the stationary contacts l8 and 'l l, While the contact9 engages stationary contacts [2 and it. Also, the movable contact M ofthe switch box SB is in-its u per position and provides an electricalconnection-between the stationary contact l and IB. Q When the switchcontrol lever SML is moved. to the reverse position'R so as to energizethe contactor RWR and deenergize the contactor and if, at that time theswitch points are iii-their normal-position as shown in the drawi'n'g,acircuitwill then be established to energize the switch machine motorand operate the switch points to the-reverse -position. This circuit maybe traced as follows: from including front -*contact 25 of contactorRWR; back contact 26 of contactor NWR, line RW, stationary contact I3,movable contact 9' in a normal position, stationary contact 12, wire 21,motor armature A, wire zsfistationary contact H, movable contact 8 in anormalposition,stationary contact I9, field wind- 'ing'-'F,'c0ntro1-wire C, and front contact 28 of contactor RWR', to As-a result of thiscircuit' being: established, the switch machine motor isso energized asto drive the switch points to their reverse positions. As the switchpoints move from their normal positions, the movable contact Hiin theswitch-box SB moves to its center position where it cannot make contactwith-either-pair of stationary contacts, 1. e. contacts l5 and It orcontacts 2| and 2.2. The contact i trem-ains in this mid-position untilthe end of the switch operating stroke when the switch points reach thereverse position, at which time -it is moved-to: a reverse position tomake a connection between stationary contacts 2| and '22. The movablecontacts8 and 9 of the switch machine, however, remain in the positionsshown during the first part of the operating stroke and move-to theirdotted line reverse positions only at theend of the operating stroke.When they 'move to these positions, the above described motor circuit isopened and the motor comes to rest, thereby stopping the switchoperation.

If the lever SML is now returned to its normal position N, the contactorRWR Will be deener- 1 gized and the contactorNWR energized. As aresult," a-circuit will then be established from ,through-front contact26 of contactor NWR, backcontact 25 of contactor RWR, wire NW,stationary contact 26,;movable contact 9 in a I reverse position,stationar contact i8,wire 29, motor-armature A, wire '27, stationarycontact l-fli movable contact 8 in a reverse position, stationarycontact 1-0, field winding F, control wire 0, and front contact 3!] ofcontactor NWR, to The motor is thus energized and the direction ofcurrent flow through its armature A is such as to drive the switchpoints to their normal positions. It will be noted that in this case, asin the previously described circuit which 'causes'operation of theswitch points to thereverse position, the unused control wire is shortedto the common wire C through a back contact of one of the contactors NWRor RWR." Thus, in this latter circuit the control wire RW is shorted tothe common wire C through back contact 28 of contactor RWR. Thisarrangement tends to prevent the inadvertent application of energy to acontrol wire which might result in erroneous operation.

From the foregoing description, it can be seen that the operation of theswitch machine motor shown in Fig. 1 is dependent upon the condition ofthe contactors NWR. and RWR. Thus, if the contactor NWR'is picked up andthe contactor RWR dropped away, the switch points will be operated fromthe reverse to the normal position; whereas, if the contactor RWR ispicked up and the contactor NWR. dropped away, the switch points will beoperated from the normal to the reverse position.

As previously noted, the control circuit from the control lever SML tothe contactors RWR and NWR. includes a front contact 3| of the trackrelay TR. For this reason, if a train should enter the detector tracksection DT and cause the track relay TR to drop away, the contactors NWRand RWR would then no longer be subject to control over the line wires 5and 6. This circuit arrangement precludes the possibility of initiatingan operation of the switch points after a train has entered the detectortrack section.

It is desired, however, that a switch movement, once begun, be completedeven though the detector track section becomes occupied and causes thedropping away of the track relay TR. The control circuit of the presentinvention provides for this contingency by means of the stick circuitsfor the contactors NWR and RWR. More specifically, the movable contactI4 of the switch box SB does not engage either pair of stationarycontacts when the switch points are in midstroke. Consequently, bothrepeater relays NWP and RWP will be dropped away under suchcircumstances. If the switch is being operated to its reverse positionso that front contact -32 of the contactor RWR is closed, a stickcircuit will then be completed through this'front contact 32 and alsoback contacts 33 and 34 of the repeater relays RWP and NWP respectively.In this way,

the condition of the contactors RWR and NWR as called for by the controllever SML will be maintained through this stick circuit even though thedetector track section DT, becomes occupied and opens front contact 3|,thereby allowing completion of the operating stroke. If the switchmachine SM is being operated to its normal position when the detectortrack circuit becomes occupied, a similar stick circuit is establishedincluding the front contact 35 of contactor NWR. g

If the switch SW has been operated to the normal position as shown inthe drawing, and is then trailed through by a train or car moving fromthe siding onto the main track, the switch points will be forced to thereverse position independently of the power operation of the switch-machine SM, as has been pointed out. This is because the switch machineSM includes the yieldable cam connection with biasing spring which actsto throw the switch points to their full reverse position when they aretrailed reverse without the operation of the switch machine drivingmotor. As a result, the movable contact I4 in the switch box SB is thenimmediately moved to its lower dotted line position thereby causing therepeater relay NWP to drop away and the energizing instead of therepeater relay RWP. In making such a trailing point train movement, thetrack relay TR, is, of course, shunted and closes its back contact 36while opening its front contact 3!. The opening of this'front contact 3|prevents manual control of the contactors NWR. and RWR over the linewires 5 and 6. However, with the front contact 31 of repeater relay RWPnow closed, an alternate circuit is completed through this front contact31 and back contact 36 of relay TR to energize the contactor RWR. Thecontactor NWR, on the other hand, cannot be held up through its upperwinding because of the open front contact 3|, nor can it be held upthrough its lower winding because of the open back contact 33 in itsstick circuit and the open front contact 38 of the relay NWP. Thus, withthe contactor RWR energized and the contactor NWR dropped away, theswitch machine motor will immediately be operated in the direction whichwill bring its operating mechanism into correspondence with itspreviously train actuated switch points.

When the train then moves out of the detector track section DT, andallows the track relay TR, again to be picked up, the opening of backcontact 36 of this track relay opensthe alternate circuit to the lowerwinding of the contactor RVVR allowing it to drop away, while theclosing of front contact 3! of relay TR restores the control of thecontactors NWR. and RWR to the manually operable lever Sm as effectedover the line wires 5 and 6. If the control lever SML has in themeanwhile been left in its normal by a train passing along the maintrack, the re peater relay NWP will be energized and a similar 'circuitestablished through front contact 38 of this relay NWP and back contact36 of track relay TR to energize the'lower winding of the 1 contactorNWR. In a similar manner, the witch operating mechanism SM will then beoperated to correspond with the trailed through switch points.

Modification of Fig. 2

The accompanying Fig. 2 shows a detector track section DT which isassociated with the stretch of track adjacent the turn out switch SW andincluding the fouling section of this switch. The track relay TB isenergized by a track battery I which has included in series therewith acurrent limiting resistor 2. The position of the switch points SW isshown diagrammatically as being controlled by the switch machine ZSM,and the position of the switch points SW, in turn, governs the operationof the switch repeater contacts included in th switch machine ZSM.

A switch machine lever SML located at the control office operates thepole changing contacts 3 and 4 to apply steady energy of either polarityfrom the battery B to the line wires 5 and 6. With the lever SML in thenormal poare in either the mid-stroke or full reverse positions,respectively.

.When the switch machine control lever 'SML is moved to the reverseposition R so as to energize the contactor RWR and deenergize thecontactor NWR and if, at that time, the switch points are in theirnormal. position as shown'in thev drawing, a circuit will then beestablished to'ene'rgize the switch machine motor and operate the'switchpoints to the reverse position. This circuit may be traced as follows:from includingfront contact of contactor RWR, back contact 26 ofcontactor NWR, the line wire RW, stationary contact l3, movable contact9, stationary contact l2, wire 21, motor armature A,wire' 29, stationarycontact II, movable contact 8, stationary contact I0, field winding F,control wire C, and front contact 28 of contactor. RWR, to As a resultofthis circu'itbeing established, the switch machine motor is 'soenergized as to drive the switch points to their reverse positions.

Ina'ddition to the above described circuit being-completed for theenergization of Y the switchfmachine motor, a circuit is alsocompletedithrough front contact 25 of contactor RWR, back contact 26 ofcontactor NWR, wire RW, magnet winding'54, stationary contact 44,movable contact' 40, stationary contact 43, .to thereby energizing themagnet 54. As indicated by the'dotted lines, this magnet 54, whenenergized, holds the movable contacts 8 and 9 in'ltheir upper positions.A similar magnet 55 is provided which, when energized, retains themovable contacts 8 and 9 in their lower positions. I As theswitch pointsSW move from the normal to-the reverse position, the movable contacts 8'and'S remain in their upper positions to keep the motor energized butas the switch points finally'reach the full reverse position, themovablefcontacts 4D and 49 move to the positions 40b'and 491). Withthesecontacts and 49 in this position, the above described circuit forthe energiz ation of magnet winding 54- is interrupt ed a result,themovable contacts 8 and 9' are permitted to be mechanically moved tothe positions .86 and 9b. When this action occurs, the circuitffor theenergization of the switch machine motor is broken and the motor becomesdeenergi 'ed, thereby stopping the switch operation'.

If thelever SML is now returned to its normalfposition N, the'Tco'ntaot'or' RWR willb e deenergized and the contactor NWR energized.As a' result, a circuit will then beestablished from ,,including frontcontact 26 of contactor NWR, back contact25 of contactor RWR, wireNWystationary contact 20, movable contact 917, stationary contact I9,wire 29, motor armature AQwire' 2'1, stationary contact l8, movable contact 8b; stationary contact I0, field winding F, controlwlre C, andfront contact 30 of contactor NWR,"to The switch machine motor is thusenergized and the direction of current flow through its armature A isnow of such a polarwas to drive the switch points from the reverseposition to the normal position. It will be noted that-in this case, asin the previously described circuit for operation of the switch pointsto the reverse position, the unused control wire is shorted to thecommon wire C through a back'contact of one or'the other of thecontactors NWR or RWR. Thus, in this latter circuit the control wire RWis shorted to the common wire C through back contact 28 of contactorRWR.

This arrangement tends" to prevent the mad vertent application of energyto a control wire which might result in erroneous operation From theforegoing description, itcan be seen that the operation of the switchmachine motor shown in Fig. 2 is dependent upon the condition of thecontactors NWR and RWR. Thus, if'the contactor NWR is picked up and thecontactor RWR dropped away, the switch points SW will be operated fromthe reverse to the normal position; whereas, if the contactor RWR ispicked up and the contactor NWR dropped away, the switch points will beoperated from the normal to the reverse position.

As previously noted, the control'circuit from the control lever SML tothe contactors RWR and NWR includes a front contact 3i of the trackrelay TR. For this reason, if a train should enter the detector tracksection DT and cause the track relay TR to drop away, the contactors NWRand RWR. will then no longer be subject to control over the line wires 5and 6. This circuitarrangement precludes the possibility of initiatingmovement of the switch points when a train is in the detector tracksection.

It is desired, however, that, if operation of the switch points has beeninitiated, it will be com.-

pleted even though the detector track sectionDT becomes occupied andcauses the dropping away of thetrack relay TR. The control circuit or-,

ganization of the present invention provides for this contingency bymeans of'the stick circuits for the contactors NWR and RWR governed by.contacts 4| and 50. For example, if the switch points are operated, aspreviously described, from the normal to the reverse position, themovable contacts 4| and 50 will assume the positions 411; and 56arespectively, as soon as the switch points move away from the fullnormal position and will remain in that position until the switchpointshave reached the full reverse position at which time the movablecontacts 4| and 50 will assume the positions M2; and 50b. However, whilethese movable contacts are in the positions 4 la and 50a, a circuit iscompleted from including stationary contact 45, movable contact 4|,stationary contact 46, movable contact 500., stationary contact 52, wire53, back contact 56 of contactor NWR, front contact 51 of contactor RWR,and the lower winding of contactor RWR, to By this means,the'contactor'RWR will remain energized even though a train has enteredthe detector track section DT, while the switch machine 2SM was inmid-stroke, and the switch points SW will continue to be operated to thereverse position.

If the detector track section DT becomes occupied when the switch pointsare being moved from the reverse to the normal position, a similarcircuit will be established including the front contact 56 and the backcontact 51; and this circuit will likewise maintain the contactor NWR inan energized condition until the switch points have reached the fullnormal position. In this way, the condition of the contactors RWR andNWR, as called for by the control lever SML, will scriptionjthat whentheswitch points are ope r ated from the normal to the reverse position,the

contactor NW3, is dropped away and the contactor RWRpicked up. ,If.howevenjthe' detftwri garter track" section D'I should become occupiedwhile I 48 movable'c'ontact 42', stationary contact 31 and the lowerwinding of contactor NWR to, energize the'contactor NWR and pick up itsfront contacts; Also, the switch machine ZSM would then be-jinflmid-stroke so that" a stick circuit, similar tothatpreviouslydescribed, would be established to-maintain the contactorRWR, in an energized condition. Although both contactors RWR and NWRwould thus be momentarily picked up, the opening of back contact 56 ofcontactor NWR would open the stick. circuit for contactor RWR so fithatonly the contactor NWR would'remain pickedup.

According to the previous description; the magnet 54 is" energized whenthe switch machine is being operated to the reverse position. However,with the switch machine in mid-stroke the movable contacts ifi andv 49are in the positions ita andASa, respectively, so that'eith'er magnet 54or 55 can then be energized, provided only that its-associated wire RWor NW, respectively, is at that time energized. In the case now underconsideration, the reversal of conditionswith respect to the contactorsRWR and NWR caused by the entrance of a train into the detector tracksection DT when the switch'points are only partially opera-ted willresult in the removal of energy from wire'RW and at the same'time applyenergy to the wire NW. As a result, the magnet 54 will becomedeenergized and the magnet 55' energized; Thus,-although the; movablecontacts 8 and 9 would ordinarily remain their upper positions until theswitch points have reached the full reverse position, theenergizationof' this magnet 55 causes the movable contacts 8 and'9 to bequickly moved to their positions 812 and so. For this reason, thepreviously described circuit for the energization of the switch machinemotor which causesthe switch points to be operated to the normalposition'is now completed and the switch points are immediately returnedto that position.

This operation occurs because the movable contact 42 follows the switchpoints as they are moved between their extreme positions. The fixedcontact 4'! is preferably constructed toallow the movable contact 42 tomake connection be tween it and the fixed contact 48 for'abcut onethirdof the operating travel of the switch points adjacent their normalposition; whereas, the fixed contact GU-is adjusted to allow the movablecontact 42 to make connection between'itand the fixedcontact 48for"about'one-third of the operating'travel'of the'switch pointsadjacent their reverse'position. Thus, the movable contact 42 doesnotmake any connection during about onethird of' the intermediate'portionof an operating stroke. It is of course to be understood that theseproportions of the operating' strcke are selected for convenience inthedisclosure and other applied to the lower winding 'of either. contactorNWR or RWR so that the contactor RW'R which has been picked up' for thefeverse'operation' of theswitch'machine, will remain picked 12 upthrough its stick circuitincludingmovable contact 50 in its position50a. This causes. the pole changing magnet54 to continue to beenergized'and the contacts 8 and 9 to be maintained in their positionsto effect the continued reverse operation of the switch machine in spiteof the occupancy of the detector track section. It should be noted,however, that if the track switch has operated sufficientlyreverse so asto close a circuit to supply energy through the back con-- tact 62 ofthe track relay TR, and through movable contact 42 in its position b,then the lower winding of contactor RWR is merely supplied with anauxiliary energizing circuit in multiple with its stick circuit alreadyenergized. This circuit continues to remain closed, even after theswitch machine 2SM has completed its operating stroke'and has opened thestick circuit, until the detector track section DT becomes unoccupiedallowing the track relay TR to pick up and open back contact 62. v

A similar operation will occur if the switch machine ZSM is operatingthe switch points of thetrack switch SW to their normal positions whenthe detector track section DT becomes occupied. In brief, it may be saidthat the entrance of a train into the detector track section DT whilethe switch SW is being operated, causes the switch machine to continueoperation so 'asto move the switch points to a full normal or reverselocked position, but if such occupancy occurs before the points havebeen moved more than one-third of the distance to the new position,theywill be returned to their original positions.

Inother words, the entrance of a train into the detector track sectionwhile the switch machine is operating the switch points, results in theswitch points being returned to their original positions if they havebeen moved something less than one-third of the distance to the oppositeposition, but their movement will be continued to the opposite positionif they have moved more than one-third of the operating stroke. In thisway the switch points are assured of being operated -to a full normal orreverse position for the passage of a car. In this connection, will beunderstood that the detector track sectionex+ tends sufliciently inadvance of the switch'S W to allow such a completion of the operatingstroke for the usual speeds at which cars approach the switch.

If the switch SW is in the normal position" as shown in-Fig. 2 and isthen trailed through'b'y a train or car moving from the siding onto themain track, the switch points will be forced out of the full normalposition regardless of the locked condition of the switch machine 28M.which is permitted by reason of the conventional spring switcharrangement associated with the front tie rod and operating bar 64.Thisyieldable connection has beenshown diagrammatically in Fig.2 by thesprings 59. Althougha trailing point train-movement of this type whichforces the'switch points from their-last actuated position may notnecessarilyforce theswi-tclr points fully over to the opposite position,such;-a' trainmovem'ent is certain to move the switch points'at leastmore than two thirds of the way,

toflthe trailed through position. As has been pointed out, movablecontact 42 substantially follows the position of the switch pointsso-that when the switch points are forcibly moved fromthe normalposition to approach the reverse posi tion by a trailing point trainmovement,1the mov-' able contact 42 will be operated to a position.

tact 48, movable contact 42, stationary contact 60, Wire 63, and lowerwinding of contactor RWR, V

to As a result, the contactor RWR will become energized.

Since the entrance of the train into the detector track section DT whichis now assumed to be trailing the switch points, caused the opening offront contact 3| of track relay TR immediately upon such entrance, thenormal contactor NWR is deenergized at the time the reverse contactorRWR is picked up. Thus, the switch machine 25M is caused to immediatelyoperate to its full reverse locked position which causes theswitchpoints to be held in their reverse positions for continued passageof the train. It can thus be seen that such operation obviates anyintermittent movement of the switch points during the trailing pointmovement of the train after the initial movement of the points by theleading initiated after the detector track section becomes occupied.

Having described two forms of a switch machine control circuitorganization as specific Bll'h' bodiments of the present invention, itis desired to be understood that these forms are selected to facilitatein the disclosure of the invention rather than to limit the number offorms which it may assume: and, it is to be further understood thatvarious modifications, adaptations, and alterations may be applied tothe specific forms shown to meet the requirements of practice, withoutin any manner departing from the spirit or scope of the presentinvention.

What I claim is:

A switch control system for the power operation of a track switchcomprising in combination,

a detector track circuit, manually operable means for designatingrespective normal and reverse positions for the control of said trackswitch, an electric switch machine for the power operation of said trackswitch having a reversible electric wheels of the train. This savesconsiderable wear track Section the track relay TR will again 23-5;-tively energizing a particular one of the windbe picked up and frontcontact 3i will become closed while back contact 62 will be opened. Thecircuit just described for the energization of the lower winding ofcontactor RWR will then be interrupted and the control of the contactorsRWR and NWR, will then revert to the polar control transmitted over linewires 5 and 6.

If the lever SML has, in the meanwhile been left in the normal positionN, the switch machine will then be immediately operated to return theswitch points to the normal position.

Obviously, if the switch points are-forced out of their full reverseposition by a train making a trailing point move along the main track, a

similar circuit will be established through back By using a controlcircuit of this type, it becomes unnecessary to operate the switchmachine control lever to bring the switch operating means intocorrespondence with the trailed through switch points prior to returningthe points to their original position. By means of the present inventionnot only is the operating mechanism 1 brought into correspondence withthe switch points and the switch points instantly brought to the fulltrailed through position, but the switch points are immediately returnedto their last actuated position when the train making the trailing moveleaves the associated detector track section. In addition, switchoperation is prevented from being motor drive and having a yieldableconnection between its driving mechanismv and said track switch, wherebysaid track switch can be operated by the passage of a train when trailedindependent of the electric driving mechanism, double Wound respectivenormal and reverse switch ma chine control contactors, circuit means forselecings of said normal and reverse switch control contactors, thecontactor selected for energization being in accordance with the normalor reverse switch position designated by said manually operable means,said circuit means being effective only provided that the switch controlcontactor for the other switch position is dropped away, normal andreverse switch position repeaterrelays' having circuit control meansef-' fective to energize each of these relays when in correspondencewith the respective 'full-normal or full-reverse position of the trackswitch, stick circuit means acting upon the other of said windings ofsaid normal and reverse switch control contactors to maintain theassociated contactor energized whenever said normal and reverse switchposition repeater relays are both dropped away, auxiliary circuitcontrol means for energizing said other winding of either of saidcontactors when said switch position repeater relay for the oppositeswitch position has been picked up by reason of the forcing of theswitch points REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 1,706,851 Howe Mar. 26, 19291,854,602 Prescott Apr. 19, 1932 2,082,933 Young et a1 June 8, 19372,183,694 Rees Dec. 19, 1939

